Many info about method, measurement area, repeatability, the measurement process, measurement process, instrument, measurement repeatability, and repeatable measurement are described inside the paper. The following are some excerpt from the paper:

One of the key elements in successfully utilizing a color control system is the accurate and repeatable measurement of the samples being evaluated. Poor technique in sample measurement will greatly diminish the accuracy of the formulas produced by shade matching software and will provide misleading results from quality control software. Measurement Technique Before any permanent samples are measured and stored into the computer database, a repeatable measurement technique must be established and observed.